Powerful impacts and falls are an (1) part of American football, the most popular sport in the United States.
In 2010, the National Football League (2) that despite protective helmets players often suffer dangerous (3) , leading to a life-long brain injury called "chronic traumatic encephalopathy."
Scientists at Cardiff and Cambridge universities say with the help of a supercomputer, they produced a multi-layered material that (4) the energy of impact much better than currently used polymer foams.
“It is a series of folds based on origami. So if you were to stack a series of playing cards at home, perhaps then you would come up with a (5) that might not look too dissimilar to this," said Peter Theobald of Cardiff University.
Testing geometrically complex shapes, researchers found that by changing the (6) of cell walls they could activate the ability of the material, they named C3, to (7) impacts from various angles.
Samples printed in a 3-D printer were tested for impacts and the results were again (8) with computer models. Scientists say by combining 3-D printing with the standard manufacturing process of injection molding, the new material can be produced in specific shapes.
“I think with this kind of material we can more than improve the (9) of the helmet ... we can design a specific helmet, for example, for each head in the world," said Rafael Santiago of University of Sao Paulo.
Researchers say if the same design could also be printed in 3-D metal printers, it could be help protect (10) vehicles from various explosive devices.
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上期答案
1. pledges
2. effects
3. renewables
4. premature
5. conversion
6. outweigh
7. politicians
8. benefits
9. responding
10. immediately